I am a postdoctoral scholar in the Department of Pediatrics at the University of California, San Diego (UCSD), and I am applying for the K99/R00 Pathway to Independence Award to facilitate my transition to become an independent investigator of medication safety during pregnancy. My background is in epidemiology and my career goal is to conduct research regarding the risks of medication use during pregnancy on perinatal and pediatric health to inform the complex treatment decisions that women and their health care providers must make. To develop my capacity to become an independent investigator, I am proposing an intensive career development and research program. Specifically, I propose (1) to increase my knowledge of pharmacology concepts, drug information, and human teratology, (2) to gain additional experience conducting studies using prospective cohort and healthcare utilization data and disseminating findings to healthcare professionals, and (3) to strengthen my grant writing skills. I have assembled the ideal team of 5 UCSD faculty members to provide me with guidance and instruction in these areas. My primary mentor, Dr. Christina Chambers, is a leader in the field of medication safety during pregnancy. My co-mentors are: Dr. Brookie Best, an expert in clinical pharmacology during pregnancy; Dr. Grace Kuo who has expertise in health services and practice-based research; Dr. Todd Gilmer, an expert in conducting research with Medicaid data; and Dr. Ronghui Xu, who has expertise in applying biostatistics methods to studies of medication in pregnancy. The objective of the proposed research is to inform clinical decision making regarding oral corticosteroid use versus alternative treatments for asthma and autoimmune diseases during pregnancy. I am proposing to assess the association between oral corticosteroid use during pregnancy and risk for preterm birth among pregnant women with asthma and autoimmune diseases. I will compare oral corticosteroids with alternative treatments (e.g., inhaled corticosteroids and disease modifying antirheumatic drugs) and no treatment. I will use both prospectively collected cohort data and healthcare utilization data to conduct the study, and I will compare and contrast these methodological approaches. Furthermore, I will disseminate the results, within the context of previous research, to clinicians. The proposed study is responsive to the urgent public health need for information regarding the impact of oral corticosteroid use on risk for preterm birth. I will develop expertise in working with cohort and healthcare utilization data, and will gain experience comparing study methodologies and developing clinical applications related to medication safety research. Building on this innovative research, I will develop a competitive R01 grant proposal to pursue studying commonly used medications during pregnancy that have inadequate human safety data.